Rotary steam generator



A 3, 1954 R. B. KELLOGG 2,685,278'

ROTARY STEAM GENERATOR Original Filed May 2, 1945 5 Sheets-Sheet l WATER CONDENSATE FIG. I

COND NSATE WATER FUEL . INVENTOR ROBERT a xawae ATTORNEYS Aug. 3, 1954 R. B. KELLOGG 2,685,278

ROTARY STEAM GENERATOR Original Filed May 2, 1945 3 Shets-Shet 2 FIG. 2

ENT OR INV ROBERT B [(5 1.1.066

BY 444%}! P ATTORNEY:

1954 R. B. KELLOGG 2,685,278

ROTARY STEAM GENERATOR Original Filed May 2, 1945 s Sheets-Sheet 5 1N VENTOR KELLOG'G ATTORNEYS ROBERT E Patented Aug. 3, 1954 OF FKJE Original application May 2, 1945, Serial No.

591,591. Divided and this application Septemher 5, 1950, Serial No. 183,223

8 Claims. (01. 122-11) (Granted under Title 35, U. S. Code (1952),

see. 266) This invention relates to steam power plants for aircraft and. more particularly to steam power plants of the turbine type having a rotary steam enerator mounted axially on the turbine shaft.

The present application is a division of my prior application Serial No. 591,591, filed May 2, 1945, now Patent No. 2,525,804, and is directed to the steam generator and its associated feeding and control mechanism.

The object of this invention is to construct a complete steam turbin power unit for aircraft, supplying energy to the propeller, in either a pusher or tractor type installation.

Another object is to construct a relatively instantaneous and minutely controlled source of superheated steam with which to drive light high-speed geared turbines powering main propellers, primarily for use in high fiying airplanes, Where a copious supply of cool air is normally available for use in the condenser.

Another object is to provide a multi-plunger Water pump with variable controlled delivery for supplying the water to the several heater tubes in a, steam generator, having control means for simultaneously controlling the respective deliveries in accordance with the total power desired.

Another object is to provide a rotating steam generator having radially arranged heater tubes wherein the unevaporated water is held in the outer portions of the tubes by centrifugal force, and wherein ring shaped headers are used to distribute unevaporated water in the outer portions of said tubes and also to form a wall providing outer and inner passes for the hot combustion gases to pass around the heater tubes.

Another object is to provide a condenser means for a steam generator unit for aircraft comprising a series of condenser tubes, using the airstream in the nose of the aircraft for passing through the tubes as a cooling medium, and then into the combustion chambers as preheated air to support the combustion of the fuel supplied by the burners in accordance with the power desired.

Further and more specific objects will become apparent in the following detailed description of this invention having reference to the accompanying drawings, wherein:

Fig. 1 is a sectional partially diagrammatic view'of the entire unit;

Fig. 2 is a partial section taken at the line 2-2 of Fig. 1;

Fig. 3 is a partial sectional view taken at the line 33 of Fig. 1;

Fig. 4 is a diagrammatic view showing a modified arrangement of condenser which may be used in connection with the above unit, if more condenser capacity is needed;

Fig. 5 is an enlarged sectional view of the water feed pump;

Fig. 6 is an enlarged detail view of one preferred form of pump plungers, and

Fig. '7 shows another form of pump plungers wherein the plunger is retracted by resilient means.

The steam generator unit, shown for purposes of illustration in the present disclosure, consists of three main assemblies: the drum I, the generating and superheater tubing 2, and the tube feed-pump assembly 3 mounted on and attached to one end of the drum; the other parts of this unit comprising the casing t, the air preheater 5, the casing wall tubes 6, and the burners I.

The boiler drum i has a hollow alloy steel shaft 3, plugged at one end a and open or with controlled openings to the turbine nozzle block at the other end. The drum is mounted on controlled temperature roller bearings H and, 2 at or near each of its ends, and is in continuous rotation during operation. The drum is drilled radially completely around its circumference throughout its desired length, so as to mount tubes, which may be rolled, screwed, or welded into it, at the points where it is drilled.

'The generator and superheater tube surface is constructed in the form of a spider or tube ring assembly 2, the ring shaped headers 13 themselves forming the battle separating the first pass M from the second pass it as shown. It is expected that th second pass tubes It connecting the drum shaft to the ring tube headers will act as superheating surfaces, the tensile stress due to the rotational motion being entirely absorbed by the comparatively cool ring headers.

It is contemplated that unequal evaporation will, at times, be present due to fouling of fireside surfaces. At such times, there will be a tendency for the water to build up to a greater height in the tube ends El and may reach the annular tube ring headers it. At such times, water spilled into these headers will distribute itself among neighboring tubes the evaporation in which has not allowed the water level, so to speak, to reach the annular ring headers.

All tubes are straight but may be of varying lengths, as it may be desirable with closely calculated and controlled evaporations to have those in the higher temperature zone of greater length than those near the end of the pass, but in any event length of high heat zone and other tubes as well as quantity of feed per tube would be in proportion to the evaporating capacity and location.

The generator and superheating tubin" would necessarily have to be of the lightest and toughest material available, as would also the drum. These highly stressed and hi h temperature parts should be worked out as regards safety factors on the airplane design basis and by actual experiment and test rather than by any existing formulae.

The tube ieedpump assembly 3 was constructed on the order of the oil injector plunger pump now in general use on oil engines, where the service is severe, involving high speeds, handling of minute quantities, use of pressures in the order of two or three thousand pounds at the injector plungers, and requiring practically leakprooi operation. The steam generator construction requires that each individual tube in the boiler receive a predetermined and variable quantity of feed from its own individual feed pump, the combustion of fuel at the burners and the quantity of feed to the tubes varying directly and instantaneously with the speed or load interposed, there being no steam reservoir as such. The pump will therefore have as many individual plungers l8 and check valves 13- as the generator has tubes ii. The pump 3 is mounted as a unit at one end of the generator drum, concentrically with the drum, the pump barrels being bored radially with respect to the axis 26 of the drum, and the drum to all purposes being a. rotating shaft. The spaced pump walls 63 and B l define a space 65 within which the feed water circulates and across which the pump barrels 66 are mounted. The check valves 19, which open on the suction stroke and close on the exhaust stroke, are submerged in the feed water and allow the feed Water to be drawn into the pump barrels 6E and expelled into the casing wall tubes 6. The inner ends 2i of the revolving pump plungers are either resiliently or positively urged against and driven by one or more stationary eccentric earns 23 with adjustable eccentricity while in operation, for controlling the length of the individual pump strokes, and hence, the output, according to the adjusted eccentricity of the stationary cam. There may be one or more of these adjustable eccentrics stacked or assembled in axial alignment With each other for adjusting the amounts of feed from the corresponding banks of pumps, and therefore the temperatures successively in the corresponding banks or rows of tubes throughout the passes. On the other hand, after suitable tests and de velopment in operation, it may be possible to employ a single adjustable eccentric for all the tubes, designed to fit the conditions obtained through out the range of load in any generator. The inner pump drive sleeve or eccentric 23 is vertically adjustable and forms the inner ring of a pin roller type of bearing 24 supporting the outer eccentric drive or cam sleeve 25.

The inner ring 23 is restricted against rotation but is vertically adjustable by means of a pair of racks 2B and gears 21 one at each end Of the drive sleeve. The racks 26 are stationary, while the gears 2'! are pivotally mounted at the ends of the inner ring 23 for simultaneous operation in opposite directions by means of the rods 23 and 38 geared together at 29, 29', to turn in opposite directions by manual means 30. and operating as turnbuckles in the nuts 3!, 32, 33, and 34 swivelled on the gears 21. Thus, as the upper rod 28 is turned to draw the upper nuts 31 and 33 toward each other the lower rod 38 pushes the lower nuts 32 and 3t further apart, and vice versa, so that the gears 21 are simultaneously turned in opposite directions to either lower or raise the drive sleeve to decrease or increase its eccentricity relative to the axis 26 of the rotating member in which the pump plungers are mounted to decrease or increase their strokes, respectively, and thus control the amount of water fed to the tubes. This feed water control may be interconnected, as at 35, with the control 36 of the fuel supply to the burners, so as to simultaneously regulate the feed water and fuel in accordance with the power de mands.

The generator as a working unit revolves or rotates with its axial portion 8 acting as the shaft. identically does the steam turbine spindle the axial portion 8 actin as the shaft or rotor and the generating tubes 2 as the blading, the main difference being that while the steam turbine is a heat dissipating unit this is a heat generating unit. The optimum speed or rotation of the drum is low, but should be designed to be great enough for the centrifugal forces imparted to the water in the tubes 2 to keep the water in the outer ends ll of the tubes, imparting a high density to the water thus trapped, allowing only steam vapor to overcome the pull of centrifugal forces and to make its Way inwardly to the axial portion. The high density created and mechanically imparted to the working Water is a highly important feature in this construction. The speed of the generator rotation should, however, be relatively low, depending to a considerable extent on the lateral length of the generator tubes, which means the diameter of the generator on its axial portion or shaft. An extreme turbulence in the combustion spaces 39 is obtained, gases entering from the combustion ring 58 into the first row of tubes 3! and completing the tour of both passes l4 and i5 thus scour the heating surfaces and, in a decidedly helical manner, describe a num ber of rotations relative to the generator casing 4 before reaching the gas outlets 62. In this connection, it may be possible that the pressure losses sufiered aerodynamically from obstruction to the airstream caused by the present device, at high speeds might be to some extent utilized in helping to revolve the generator, by arranging the tubes 8 in a helical manner on the inside of the drum. It must be borne in however, that the turbine 64, which is a separate unit and operating at very great rotational speeds, is nevertheless geared mechanically to the revolving generator, as the turbine cannot be operated, that is 1'0- tated, separately from the generator. A reduction gear means G5 and are interposed to drive the generator 5 at about R. P. M. and the propeller 46 at about 2000 R. P. M. when the turbine turns at 10,000 R. P. M. The means 53 also includes a thrust bearing for the propeller.

The entire steam generator-turbine unit may be started by external power means. For this purpose, as an illustration, 2, portable motor driven propeller might be used by wheeling it up to and facing the airplane propeller :15. In opcrating, the idle propeller 46 on the turbine unit begins to revolve, which in. turn, revolves the turbine 4d and thus the steam generator unit I geared to it. When sufdcient rotational speed of the steam generator i has been obtained to keep water in the tube ends I! by centrifugal force, the burners I may be lighted off and feed water supply simultaneously turned on from the pumps 3 in proportionate amount. Steam formin almost instantaneously then takes charge and the unit operates on its own until the combustion fuel and feed of the water are reduced to a stopping point. t will be noted that one end, that is the end toward the turbine of the rotating generator drum or shaft is open, and has to be sealed off without excessive leakage between the drum proper and the stationary main steam pipe or nipple having nozzle tubes 50 leading to the turbine nozzle block 55. However, this matter of sealing against the high pressures without employing rubbing type packing has already been well developed to a high degree in high pressure steam turbines, and more recently, in rotor shaft gland packing of very high temperature and pressure petroleum cracking still pumps. A preferable form of sealing means is a practically rubbed in fit of a series of labyrinth packing rings of which the laid over inverted V is used in some installations, while in many others, lantern glands and leak-offs are employed. However, this is not too difficult and is not an insurmountable problem in any case.

In order to conform to a compact packaging and streamlining of the power unit assembly, it is almost essential that directly behind the propeller in the case of a tractor type, or in the nose ll of the unit in any case, an opening 63 be provided, circular in form, similar to that normally present in all air-cooled radial internal combustion engines, but with possibly a much smaller flat plat area. In other words, at reasonable air speeds, from 60 to 300 miles per hour, and using the resistance of the flat plate formulae as found on page 59, chapter V. of Civil Aeronautics Bulletin No. 26 of 1940, it can read-' ily be appreciated that very considerable power saving would be made in reducing this area.

The quantity of air required for condensing a possible 30,000 pounds of steam per hour with a properly desig ed condenser of the type shown herein, should be not greater than that which could be passed through a flat plate area equal to that of a comparatively powered radial internal combustion engine, and through tubing having a total heat exchange surface sufficiently large, assuming a normal inside and outside temperature differential of 172 F. This is based on the assumption of a normal average temperatur of 40 F. at 8,006 feet altitude near the equator and temperature of the exhaust steam in the condenser of 212 F. after full expansion at the turbine exhaust. The total heat exchange surfac needed in the condenser under these conditions is calculate-c to be between 5000 and 10,000 sq. ft. depending upon the coefficient of heat transfer of the material used in the con denser tubes 39. This can be reasonably well provided for in the structure illustrated in Fig. 1, although an additional amount of heat exchange surface for the condenser may be provided in the wing structure of the aircraft, as shown in Fig. i, and connected with the portion in the nose of the unit, if circumstances require this.

The condenser, as incorporated in Fig. l, lends itself to streamlining which the radial engine does not. Hence, the fiat plat resistance can be reduced to begin with, and the air used for condensing can, in the meanwhile, be preheated for use in th combustion process at the burners.

The air passed through the condenser directly behind the propeller picks up the latent heat from the exhaust steam through the walls of the condenser tubes and then passes to the air preheater casing 52 completely surrounding the steam generator. A fin type wall structure may be used in these tubes to increase the heat transfer to the combustion air, or other high heat transfer means may be resorted to. The surrounding air 5! in the air preheater casing 52 forming the outside of the entire generator not only insulates the rest of the plane from the boiler furnace but also serves to maintain at all times a higher pressure in the space around the generator than in the furnace, thus preventing high furnace pressures from causing burning through th furnace Walls and endangering the adjacent plane structure.

It will be noted that two passes hi and [5 are provided for in the generator illustrated, although the structure may not be limited to only the two, as shown, but may be designed with any number of passes arranged in any form, and, if necessary, some booster burners might be provided at the beginning of the second pass IE or at any other point in the path of the hot gases throughout the boiler.

As in many other steam power plants, a portion of the steam may be bled from any point 56 of this turbine power plant and used for air ejectors, plane heating, as Well as cooling, or air conditioning.

The multiplicity of individual feed tubes necessaryin the present construction, might appear to be complicated. However, this complication is far less than the complication of structure found in a modern gasoline radial engine of comparative horsepower. Likewise, the multiplicity of pumps used might appear complicated, but they are based on the operation of fuel oil pumps for diesel engines, now in use, which have been perfected to a high degree.

A preferred form of pump plunger operating means is shown in Figs. 3, 5 and 6, although it may be of the more common form shown in 7. latter of the resilient return type, wherein a spring 55 is provided around the plunger H3 between the pump casing 3 and a shoulder on the end 0a the plunger 2% which abuts against the operating cam or eccentric sleeve In the preferred form in Figs. 3, 5 and 6, the several plungers in axial alignment are made integral with a co. which abuts against the or eccentric sleeve 25 and is held thereagainst for limited free rocking and sliding with respect thel by slip rings 5?, which are common to a series of these rods connected with all the other pump plungers outed radially around the pump casing. These slip rings provide for a positive return of the pump plungers.

Sealing are provided at Iii, and E2 between the stationary elements and the moving generator unit.

It should, therefore, be clear that a construction of the type shown herein for purposes of illustration is entirely feasible, and may be readily constructed with the modern equipment now available. Although only one form of the invention is herein shown and described, it is to be understood that variations in arrangement and construction of the various parts may be made without departing from the spirit and the scope of this invention, as defined in the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental -nzon base rod 2! purposes without the payment of any royalties thereon or therefor.

What is claimed is:

l. A steam generator unit mounted for rotation on a. shaft, said unit comprising a drum, a multiplicity of heater tubes arranged radially therein for conducting the steam generated into an axial passage in said shaft and for maintaining the unevaporated water circumferentially in the outer portions of said tubes by reason of the centrifugal forces acting thereon during rotation of the drum, a pump mounted on said drum for rotation therewith, said pump having a multiplicity of plungers each of which is operatively connected to the outer end of a separate heater tube, each of said plungers supplying a diiferent predetermined quantity of feed water to its associated heater tube, and manually adjustable means in contact with said plungers for selectivel varying the strokes thereof and thereby varying the individual quantities of feed water supplied to the separate heater tubes in accordance with power demand.

2. A rotary steam generator comprising a hollow shaft, a rotatable drum on said shaft, a multiplicity of straight heater tubes arranged radially in said drum, a multiplicity of individual pump means, each of said heater tubes being connected to a. separate pump means, each of said pump means supplying a different predetermined quantity of feed water to its associated heater tube, and control means in contact with each pump means for varying the quantity of feed water supplied to any heater tube in accord ance with the power demand.

3. A rotary steam generator comprising a hollow shaft, a rotatable drum on said shaft, a multiplicity of straight heater tubes arranged radially in said drum and in communication with the interior of said shaft, pump means mounted generally concentrically with the drum, said pump means comprising a multiplicity of indi vidual pump plungers each of which is operatively connected to a separate heater tube, each pump plunger supplying a different predetermined quantity of feed water to its associated heater tube, and an eccentric cam in contact wtih said pump plungers for selectively varying the strokes thereof and thereby varying the individual quantities of feed water supplied to the separate heater tubes in accordance with power demand.

4. A steam generator unit mounted for rotation on a shaft, said unit comprising a drum, a multiplicity of heater tubes arranged radially therein for conducting the steam generated into an axial passage in said shaft and for maintaining the unevaporated water circumferentially in the outer portions of said tubes by reason of the centrifugal forces acting thereon during rotation of the drum, a series of ring shaped headers interposed annularly between the outer and inner ends of said tubes for promoting distribution of any unevaporated water spilling over from the outer portions of some of said heater tubes into outer portions of adjacent heater tubes as a result of surface fouling on said first mentioned tubes.

5. A steam generator unit mounted for rotation on a shaft, said unit comprising a drum, a multiplicity of heater tubes arranged radially therein for conducting the steam generated into an axial passage in said shaft and for maintaining the unevaporated water circumferentially in the outer portions of said tubes by reason of the centrifugal forces acting thereon during rotation of the drum, a series of ring shaped headers interposed annularly between the outer and inner ends of said tubes for promoting distribution of any unevaporated water spilling over from the outer portions of adjacent heater tubes as a result of surface fouling on said first mentioned tubes, the ring shaped headers being placed side by side and contiguous to form a continuous cylindrical wall through the major portion of the length of the drum and thus providing outer and inner passes in said generator around said heater tubes.

6. A rotary steam generator comprising a shaft, a rotatable drum on said shaft, a multiplicity of heater tubes arranged radially in said drum for maintaining unevaporated water in the outer portions of said tubes during rotation of the drum, a series of ring shaped headers interposed in side by side contact annularly between the outer and inner ends of said tubes for promoting distribution of water spilling over from the outer portions of said heater tubes, heating means positioned radially outward from said headers and directed toward said outer portions so that the outward portion of the heater tubes will constitute the first of two passes separated by said headers.

7. The combination of claim 4 further de fined in that water feed means are connected to the heater tubes radially outwardly of said headers.

8. The combination of claim 5 further defined in that water feed means are connected to the heater tubes radially outwardly of said headers, each of said heater tubes being connected to an individual water feeding means.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,610,163 Samuelson Dec. '7, 1926 1,994,009 Vorkauf Mar. 12, 1935 2,098,841 Verloop Nov. 9, 1937 2,140,175 Starziczny Dec. '13, 1938 2,233,031 Price Feb. 25, 1941 FOREIGN PATENTS Number Country Date 612,627 Germany Apr. 30, 1935 

